S.B.
Say "thank you" and be grateful your daughters have caring grandparents. When you buy clothes for them, you can pick out what you like. Gifts are just that --gifts, not obligations. Sometimes well-meaning people hit the mark and sometimes they miss when they attempt to please with gifts. Wouldn't it be wise to teach your daughter that we always show gratitude, even if a gift isn't what we would have chosen ourselves? I know you want her to be the kind of person who looks beneath the surface and responds to the thought behind the gift. Also, your daughter is just four -- which isn't that far from being a baby! Step back and get a little perspective. In a flash she will be a pre-teen and then a teenager, consumed with clothes and trying to "fit in" and look older. Enjoy the relatively stress-free years when you can solve all her problems and simple things make her happy.
So saying, here is a suggestion for guiding your in-laws to clothing you feel more appropriate. Before the next gift-giving occasion, bring out some sale ads and say, "I thought you might like to know that there are some really cute dresses like this one on sale for a good price. Isn't it adorable?"
If that fails, smile and say thanks -- with a thankful heart!
S. B.